Construction equipment, such as a hydraulic pressure shovel, generally includes a diesel engine as a motor. The construction equipment rotates at least one capacity variable hydraulic pump by using the diesel engine. The construction equipment performs a necessary operation by driving a hydraulic actuator by pressed oil discharged from the hydraulic pump. The diesel engine includes an input means, such as an accelerator lever, for directing target revolutions per minute (RPM) of the engine, and controls the amount of fuel injected and the RPM of the engine according to the target RPM of the engine and an input load transmitted through the hydraulic pump and the like.
The construction equipment calculates a difference between the original target RPM of the engine and an actual RPM of the engine (RPM deviation) by using an RPM sensor in relation to the control of the engine and the hydraulic pump. The construction equipment performs speed sensing control for controlling an input torque of the hydraulic pump by using the calculated RPM deviation. However, in the control method, an engine control unit uses only an actual RPM of the engine as information based on which the engine is controllable in response to a large load variation transmitted from the hydraulic pump to the engine. The hydraulic load which continuously and greatly varies for operating the construction equipment is transmitted to the engine, which is mechanically and directly connected with the hydraulic pump, so that an actual RPM of the engine is decreased by an insufficient torque generation of the engine. Accordingly, the engine control unit may respond to a rapid load after the actual RPM of the engine is decreased.
In general, since the engine control unit has a very complicated control logic compared to a pump controller or a vehicle controller, the implementation of compensation control within the engine control unit demands reviews with long time and effort. Verification when the compensation control is implemented also requires much time and effort, such that product development resources are negatively increased.
Further, when the pump controller or the vehicle controller calculates a torque of the hydraulic pump, and the engine control unit performs the compensation control, accuracy of the calculated torque of the hydraulic pump is degraded, so that even though a compensation torque value is increased, only the engine control unit recognizes the increase in the compensation torque value. That is, there is also a disadvantage in that the pump controller or the vehicle controller, which calculates the torque of the hydraulic pump, cannot accurately recognize the calculated torque value.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.